feat: reasoning effort as optional (#3527)

Allow the reasoning effort to be optional

codex-rs/common/src/config_summary.rs

@@ -17,7 +17,10 @@ pub fn create_config_summary_entries(config: &Config) -> Vec<(&'static str, Stri
     {
         entries.push((
             "reasoning effort",
-            config.model_reasoning_effort.to_string(),
+            config
+                .model_reasoning_effort
+                .map(|effort| effort.to_string())
+                .unwrap_or_else(|| "none".to_string()),
         ));
         entries.push((
             "reasoning summaries",

codex-rs/common/src/model_presets.rs

@@ -12,7 +12,7 @@ pub struct ModelPreset {
     /// Model slug (e.g., "gpt-5").
     pub model: &'static str,
     /// Reasoning effort to apply for this preset.
-    pub effort: ReasoningEffort,
+    pub effort: Option<ReasoningEffort>,
 }
 
 /// Built-in list of model presets that pair a model with a reasoning effort.
@@ -26,35 +26,35 @@ pub fn builtin_model_presets() -> &'static [ModelPreset] {
             label: "gpt-5 minimal",
             description: "— fastest responses with limited reasoning; ideal for coding, instructions, or lightweight tasks",
             model: "gpt-5",
-            effort: ReasoningEffort::Minimal,
+            effort: Some(ReasoningEffort::Minimal),
         },
         ModelPreset {
             id: "gpt-5-low",
             label: "gpt-5 low",
             description: "— balances speed with some reasoning; useful for straightforward queries and short explanations",
             model: "gpt-5",
-            effort: ReasoningEffort::Low,
+            effort: Some(ReasoningEffort::Low),
         },
         ModelPreset {
             id: "gpt-5-medium",
             label: "gpt-5 medium",
             description: "— default setting; provides a solid balance of reasoning depth and latency for general-purpose tasks",
             model: "gpt-5",
-            effort: ReasoningEffort::Medium,
+            effort: Some(ReasoningEffort::Medium),
         },
         ModelPreset {
             id: "gpt-5-high",
             label: "gpt-5 high",
             description: "— maximizes reasoning depth for complex or ambiguous problems",
             model: "gpt-5",
-            effort: ReasoningEffort::High,
+            effort: Some(ReasoningEffort::High),
         },
         ModelPreset {
             id: "gpt-5-high-new",
             label: "gpt-5 high new",
             description: "— our latest release tuned to rely on the model's built-in reasoning defaults",
             model: "gpt-5-high-new",
-            effort: ReasoningEffort::Medium,
+            effort: None,
         },
     ];
     PRESETS